Structural evolution of carbon aerogel microspheres by thermal treatment for high–power supercapacitors

Abstract

In this work, a series of carbon aerogel microspheres (CAMs) with tailored pore structures were successfully prepared via a sol–gel method and subsequent heat–treatment at various temperatures from 600 to 1600 °C. The effects of heat–treatment temperature (HTT) on the CAM microstructure were systematically investigated by physical and chemical characterization. The electrical conductivity increased by up to 250 S/cm and mesopores with high electrolyte accessibility developed in the CAM with increasing HTT. However, the specific surface area (SSA) decreased for HTTs from 1000 to 1600 °C. The results show that these two factors should be finely balanced for further applications in high power supercapacitors. The CAMs carbonized at 1000 °C had the highest SSA (1454 m2/g), large mesoporous content (20%) and favorable conductivity (71 S/cm). They delivered a high energy density of 38.4 Wh/kg at a power density of 0.17 kW/kg. They retained an energy density of 25.5 Wh/kg even at a high power density of 10.2 kW/kg, and a good rate capability of 84% after 10,000 cycles. This performance is superior to, or at least comparable to, those of most reported carbon materials.